// SPDX-License-Identifier: GPL-2.0+
/*
 * I2C multi-instantiate driver, pseudo driver to instantiate multiple
 * i2c-clients from a single fwnode.
 *
 * Copyright 2018 Hans de Goede <hdegoede@redhat.com>
 */

#include <linux/acpi.h>
#include <linux/bits.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/types.h>

#define IRQ_RESOURCE_TYPE       GENMASK(1, 0)
#define IRQ_RESOURCE_NONE       0
#define IRQ_RESOURCE_GPIO       1
#define IRQ_RESOURCE_APIC       2

struct i2c_inst_data {
        const char *type;
        unsigned int flags;
        int irq_idx;
};

struct i2c_multi_inst_data {
        int num_clients;
        struct i2c_client *clients[];
};

static int i2c_multi_inst_count(struct acpi_resource *ares, void *data)
{
        struct acpi_resource_i2c_serialbus *sb;
        int *count = data;

        if (i2c_acpi_get_i2c_resource(ares, &sb))
                *count = *count + 1;

        return 1;
}

static int i2c_multi_inst_count_resources(struct acpi_device *adev)
{
        LIST_HEAD(r);
        int count = 0;
        int ret;

        ret = acpi_dev_get_resources(adev, &r, i2c_multi_inst_count, &count);
        if (ret < 0)
                return ret;

        acpi_dev_free_resource_list(&r);
        return count;
}

static int i2c_multi_inst_probe(struct platform_device *pdev)
{
        struct i2c_multi_inst_data *multi;
        const struct i2c_inst_data *inst_data;
        struct i2c_board_info board_info = {};
        struct device *dev = &pdev->dev;
        struct acpi_device *adev;
        char name[32];
        int i, ret;

        inst_data = device_get_match_data(dev);
        if (!inst_data) {
                dev_err(dev, "Error ACPI match data is missing\n");
                return -ENODEV;
        }

        adev = ACPI_COMPANION(dev);

        /* Count number of clients to instantiate */
        ret = i2c_multi_inst_count_resources(adev);
        if (ret < 0)
                return ret;

        multi = devm_kmalloc(dev, struct_size(multi, clients, ret), GFP_KERNEL);
        if (!multi)
                return -ENOMEM;

        multi->num_clients = ret;

        for (i = 0; i < multi->num_clients && inst_data[i].type; i++) {
                memset(&board_info, 0, sizeof(board_info));
                strlcpy(board_info.type, inst_data[i].type, I2C_NAME_SIZE);
                snprintf(name, sizeof(name), "%s-%s.%d", dev_name(dev),
                         inst_data[i].type, i);
                board_info.dev_name = name;
                switch (inst_data[i].flags & IRQ_RESOURCE_TYPE) {
                case IRQ_RESOURCE_GPIO:
                        ret = acpi_dev_gpio_irq_get(adev, inst_data[i].irq_idx);
                        if (ret < 0) {
                                dev_err(dev, "Error requesting irq at index %d: %d\n",
                                        inst_data[i].irq_idx, ret);
                                goto error;
                        }
                        board_info.irq = ret;
                        break;
                case IRQ_RESOURCE_APIC:
                        ret = platform_get_irq(pdev, inst_data[i].irq_idx);
                        if (ret < 0) {
                                dev_dbg(dev, "Error requesting irq at index %d: %d\n",
                                        inst_data[i].irq_idx, ret);
                                goto error;
                        }
                        board_info.irq = ret;
                        break;
                default:
                        board_info.irq = 0;
                        break;
                }
                multi->clients[i] = i2c_acpi_new_device(dev, i, &board_info);
                if (IS_ERR(multi->clients[i])) {
                        ret = dev_err_probe(dev, PTR_ERR(multi->clients[i]),
                                            "Error creating i2c-client, idx %d\n", i);
                        goto error;
                }
        }
        if (i < multi->num_clients) {
                dev_err(dev, "Error finding driver, idx %d\n", i);
                ret = -ENODEV;
                goto error;
        }

        platform_set_drvdata(pdev, multi);
        return 0;

error:
        while (--i >= 0)
                i2c_unregister_device(multi->clients[i]);

        return ret;
}

static int i2c_multi_inst_remove(struct platform_device *pdev)
{
        struct i2c_multi_inst_data *multi = platform_get_drvdata(pdev);
        int i;

        for (i = 0; i < multi->num_clients; i++)
                i2c_unregister_device(multi->clients[i]);

        return 0;
}

static const struct i2c_inst_data bsg1160_data[]  = {
        { "bmc150_accel", IRQ_RESOURCE_GPIO, 0 },
        { "bmc150_magn" },
        { "bmg160" },
        {}
};

static const struct i2c_inst_data bsg2150_data[]  = {
        { "bmc150_accel", IRQ_RESOURCE_GPIO, 0 },
        { "bmc150_magn" },
        /* The resources describe a 3th client, but it is not really there. */
        { "bsg2150_dummy_dev" },
        {}
};

/*
 * Device with _HID INT3515 (TI PD controllers) has some unresolved interrupt
 * issues. The most common problem seen is interrupt flood.
 *
 * There are at least two known causes. Firstly, on some boards, the
 * I2CSerialBus resource index does not match the Interrupt resource, i.e. they
 * are not one-to-one mapped like in the array below. Secondly, on some boards
 * the IRQ line from the PD controller is not actually connected at all. But the
 * interrupt flood is also seen on some boards where those are not a problem, so
 * there are some other problems as well.
 *
 * Because of the issues with the interrupt, the device is disabled for now. If
 * you wish to debug the issues, uncomment the below, and add an entry for the
 * INT3515 device to the i2c_multi_instance_ids table.
 *
 * static const struct i2c_inst_data int3515_data[]  = {
 *      { "tps6598x", IRQ_RESOURCE_APIC, 0 },
 *      { "tps6598x", IRQ_RESOURCE_APIC, 1 },
 *      { "tps6598x", IRQ_RESOURCE_APIC, 2 },
 *      { "tps6598x", IRQ_RESOURCE_APIC, 3 },
 *      { }
 * };
 */

/*
 * Note new device-ids must also be added to i2c_multi_instantiate_ids in
 * drivers/acpi/scan.c: acpi_device_enumeration_by_parent().
 */
static const struct acpi_device_id i2c_multi_inst_acpi_ids[] = {
        { "BSG1160", (unsigned long)bsg1160_data },
        { "BSG2150", (unsigned long)bsg2150_data },
        { }
};
MODULE_DEVICE_TABLE(acpi, i2c_multi_inst_acpi_ids);

static struct platform_driver i2c_multi_inst_driver = {
        .driver = {
                .name = "I2C multi instantiate pseudo device driver",
                .acpi_match_table = i2c_multi_inst_acpi_ids,
        },
        .probe = i2c_multi_inst_probe,
        .remove = i2c_multi_inst_remove,
};
module_platform_driver(i2c_multi_inst_driver);

MODULE_DESCRIPTION("I2C multi instantiate pseudo device driver");
MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
MODULE_LICENSE("GPL");